资源环境科技发展态势分析平台

Since 2013, the winter mean fine particulate matter (PM_2.5) had been decreased significantly due to stringent emission controls in most of China. Nevertheless, we found a seesaw pattern of PM_2.5 interannual anomalies between Beijing-Tianjin-Hebei (BTH) and Yangtze River Delta (YRD). Using the multiple linear regression method, meteorology-driven PM_2.5 interannual anomalies show that the low (high) PM_2.5 relative difference between BTH and YRD (RD_B&Y) was associated with the strong (weak) East Asian winter monsoon (EAWM). The strong EAWM transported more air pollutants from BTH to YRD. During the COVID-19 lockdown period, due to the weak EAWM, air pollution still occurred in northern BTH, while the PM_2.5 was relatively low in YRD, causing high RD_B&Y values. Our results imply that the activity of EAWM and characteristics of regional transport have obvious interannual variations, which is indispensable in evaluating the achievements of PM_2.5 quality management between up and downstream regions.